[fix](ut) fix a potential memory leak in BE ut

```
 ==12681==ERROR: LeakSanitizer: detected memory leaks
 Direct leak of 128 byte(s) in 1 object(s) allocated from:
     #0 0x562b93d0fc57 in operator new(unsigned long) (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x16e02c57)
     #1 0x562b955fd176 in doris::ArrowWorkFlowTest::init_runtime_state() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:92
     #2 0x562b955fcf58 in doris::ArrowWorkFlowTest::init() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:87
     #3 0x562b9560ba7d in doris::ArrowWorkFlowTest::SetUp() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:61
     #4 0x562b9f38263c in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/
     #5 0x562b9f37ca78 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/
     #6 0x562b9f3540e1 in testing::Test::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224470e1)
     apache#7 0x562b9f354b7f in testing::TestInfo::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x22447b7f)
     apache#8 0x562b9f35543f in testing::TestSuite::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x2244843f)
     apache#9 0x562b9f364aff in testing::internal::UnitTestImpl::RunAllTests() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x22457aff)
     apache#10 0x562b9f3833ed in bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (Impl::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224763ed)
     apache#11 0x562b9f37d932 in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), e/ut_build_ASAN/test/doris_be_test+0x22470932)
     apache#12 0x562b9f3632f4 in testing::UnitTest::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224562f4)
     apache#13 0x562b95369a7c in RUN_ALL_TESTS() /var/local/thirdparty/installed/include/gtest/gtest.h:2490
     apache#14 0x562b95366048 in main /root/doris/be/test/testutil/run_all_tests.cpp:43
     apache#15 0x7f40dcbb6554 in __libc_start_main (/lib64/libc.so.6+0x22554)
 Direct leak of 104 byte(s) in 1 object(s) allocated from:
     #0 0x562b93d0fc57 in operator new(unsigned long) (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x16e02c57)
     #1 0x562b955fd213 in doris::ArrowWorkFlowTest::init_runtime_state() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:93
     #2 0x562b955fcf58 in doris::ArrowWorkFlowTest::init() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:87
     #3 0x562b9560ba7d in doris::ArrowWorkFlowTest::SetUp() /root/doris/be/test/util/arrow/arrow_work_flow_test.cpp:61
     #4 0x562b9f38263c in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/
     #5 0x562b9f37ca78 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/
     #6 0x562b9f3540e1 in testing::Test::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224470e1)
     apache#7 0x562b9f354b7f in testing::TestInfo::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x22447b7f)
     apache#8 0x562b9f35543f in testing::TestSuite::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x2244843f)
     apache#9 0x562b9f364aff in testing::internal::UnitTestImpl::RunAllTests() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x22457aff)
     apache#10 0x562b9f3833ed in bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (Impl::*)(), char const*) (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224763ed)
     apache#11 0x562b9f37d932 in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), e/ut_build_ASAN/test/doris_be_test+0x22470932)
     apache#12 0x562b9f3632f4 in testing::UnitTest::Run() (/root/doris/be/ut_build_ASAN/test/doris_be_test+0x224562f4)
     apache#13 0x562b95369a7c in RUN_ALL_TESTS() /var/local/thirdparty/installed/include/gtest/gtest.h:2490
     apache#14 0x562b95366048 in main /root/doris/be/test/testutil/run_all_tests.cpp:43
     apache#15 0x7f40dcbb6554 in __libc_start_main (/lib64/libc.so.6+0x22554)
 SUMMARY: AddressSanitizer: 232 byte(s) leaked in 2 allocation(s).
```

be/test/util/arrow/arrow_work_flow_test.cpp

@@ -65,6 +65,7 @@ class ArrowWorkFlowTest : public testing::Test {
         EXPECT_EQ(system("rm -rf ./test_run"), 0);
 
         delete _state;
+        doris::ExecEnv::destroy(_exec_env);
     }
 
     void init();